1888.] Gr. M. Giles— Notes on the Amphipoda of Indian Waters. 233 



mandibles are of even more complex structure, their cutting and tritura- 

 ting plates being alike doubled. Each pair of plates is immovably con- 

 nected together, the two cutters having simple toothless chisel edges 

 and closely resembling each other in general form, while the triturating 

 plates are very peculiar, the more superficial plate being smaller than 

 the deeper and armed with short, stout, conical teeth, the most anterior 

 being blunt and considerably longer than the rest, and the deeper tritu- 

 rating plates even more complex. Most anteriorly comes a vertically 

 arranged row of three stout, bluntly conical teeth placed, it will be ob- 

 served, at right angles to the main row of triturating processes. Behind 

 this row comes a peculiar stout tooth with a trenchant bifid apex, and, 

 behind this again, a number of long stout spines of no great strength. 

 The mandibular appendage is of exceptionally great proportional size, 

 being absolutely considerably longer than the pediform ramus of the 

 maxilliped, and may often be made out projecting forwards between. 

 the roots of the antennules and antennse. The palp has four joints, 

 of which the first is very short, while the remaining three are subequal 

 and long. The last joint ends in a dense brush of long thin hairs, but 

 the remainder of the organ is nearly smooth. 



The digestive organs, as far as they were examined, closely resemble 

 those of Ampelisca lepta, the chitinous stomach being subdivided into two 

 cavities, and closely resembling that of Ampelisca in the arrangement of 

 its armature. There is the same pair of strongly armed plates at the 

 anterior extremity of the organ, and it is further notable that, as in 

 Ampelisca, the spines of these plates resemble in form those on the pos- 

 terior poi'tion of the triturating mandibular plate ; being simple pointed 

 rods, in both cases, in the present species ; and lancet-headed spines 

 in both situations in Ampelisca. The " sifting " stomach appears to be 

 of identical construction in both species. 



The second and third tJioracic appendages, or gnathopoda, present 

 considerable sexual differences. In the male, the 1st gnathopod, though 

 of but medium length, is immensely stout, being nearly as thick as the 

 body of the animal. It is furnished with a well-developed and very 

 powerful double subchela, the dactylus, which is strong and a little vari- 

 cose, but otherwise unarmed, being opposible to the nearly quadrangular, 

 very short, and hirsute propodite and the latter again to the prolonged 

 postero-inferior angle of the immensely dilated carpopodite. The 

 articulation between this latter and the meropodite is very oblique, 

 being placed much more on the anterior than on the inferior aspect of the 

 articulus. The remaining joints, though very short, present nothino- 

 remarkable. The second gnathopod in the male is short, slender, and 

 imperfectly subchelate, the dactyltis being barely opposible to the dilated, 



